As a controller suitable when using a high pressure fluid, a controller is disclosed in patent article 1 (Japanese Laid-Open Patent Publication No. H07-139648) that includes a valve main body in which a fluid passage between a valve disc and a valve ring opens and closes with the up and down movement in a reciprocating manner of a valve rod; a casing fixed to an upper part of the valve main body; an operating shaft arranged at the upper section in the casing in a freely up and down movable manner; a driving means for moving the operating shaft up and down; a power transmitting means, arranged at the lower section in the casing, for amplifying the force applied on the operating shaft and transmitting to the valve rod; a biasing means for biasing the operating shaft downward; and a pressure chamber, formed between a piston arranged on the operating shaft and a partition plate arranged below the piston and fixed to the casing, for moving the operating shaft upward when the operation gas is introduced, wherein the valve rod moves upward as the operation gas is introduced into the pressure chamber, and the valve rod moves downward by the biasing force of the biasing means as the operation gas in the pressure chamber is discharged.
In the controller of patent article 1, the movement speed of the valve rod is not taken into consideration, and that in which the opening and closing operation is rapidly performed is preferred. However, with nitrogen trifluoride (NF3) used in cleaning gas and the like of a semiconductor device, the flow rate thereof is required to be set equal to or lower than a certain value so that static electricity of the gas itself does not become the ignition source. A conventional controller is unable to support such needs.
The present invention aims to provide a controller for high pressure fluid that slowly moves the valve rod and that can be applied to gases such as nitrogen trifluoride that must be used while suppressing the flow rate.